Field of the Invention: Load manangement control apparatus and systems have been used in one form or another for many years. Such systems typically have three general modes of control which can be applied to electrical loads connected to the apparatus in order to realize monetary and energy savings. These general modes of control are: duty cycle control, time of day control and demand limit control. While each of these general modes is quite commonly known to one skilled in the art, the use of such an energy management system is described in an article entitled, "How To Use PCs for Energy Management Systems, in Control Engineering of February 1979, pages 39 to 41.
The particular mode of control entitled Duty Cycle Control provides for the programming of the off time of a particular time interval for each of the loads connected to the apparatus to reduce the operational or duty cycle of the load even though certain control apparatus associated with the load may call for its operation, in an effort to realize the monetary and energy savings. Once a duty cycle is established by the programming means the loads are sequenced and each load is turned off during the selected time period of its interval of operation to reduce electrical consumption.
The duty cycle control compensates for certain inherent system inefficiencies which cause excessive cooling or heating conditions such as the problem of placing thermostats too close or too far away from their thermal sources. A building manager may choose to duty cycle certain loads to assure that these loads are operated with a minimum amount of electrical power to reduce the overall electrical power consumption of his installation.